Composition for the ignition of rocket monopropellants



the Navy No Drawing. Fiied Feb. 28, 1957, Ser. No. 643,201 2 tilairns. (Cl. nil-35.4}

(Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to an igniter for rocket monopropellants of the type of an amine nitrate dissolved in nitric acid.

It is particularly desirable in the operation of rocket engines to use a self-combustible propellant. Such a propellant is found in an amine nitrate dissolved in nitric acid. These monopropellants are extremely stable and no satisfactory method of ignition has heretofore been developed. For utmost efficiency it is necessary that decomposition of the monopropellant be insured when the monopropellant comes into contact with the ignited. This invention assures such a result.

In accordance With the invention, a powdered metal hydride is used to ignite the monopropellant. In the principal phase, lithium hydride is mixed with an inert combustible adhesive to form the igniter. The composition described is a paste or dough that is suitably supported inside the rocket chamber so that the monopropellant may impinge upon it.

It is an object of this invention to provide an igniter for a liquid monopropellant of the type of an amine nitrate dissolved in nitric acid.

It is a further object of this invention to provide a composition of lithium hydride mixed with rubber cement as an igniter for monopropellants of the type of an amine nitrate dissolved in nitric acid.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description.

The igniter, which is most effective for monopropellants of the type of an amine nitrate dissolved in nitric acid, consists of a composition in the form of a paste or dough of an inert combustible adhesive substance mixed with a powdered metal hydride. In the preferred embodiment of the invention, lithium hydride is mixed with rubber cement (dry) to form the igniter. This presents a large surface for contact with the monopropellant. The proportions of the igniter mix in its preferred form are 85% lithium hydride and 15% rubber cement by weight.

3,115,005 Patented Dec. 24, 1963 In other forms of the invention, lithium aluminum hydride or mixtures of lithium hydride and lithium aluminum hydride are mixed with rubber cement. At times powdered magnesium metal may be mixed with the hydrides and the cement.

in the operation of the rocket motor, the dough is suitably supported inside the rocket chamber. One of the liquid monopropellants of the type of an amine nitrate dissolved in nitric acid, as described in my copending application, Serial No. 643,202, filed February 28, 1957, is directed through a spray nozzle into the rocket chamber. In the preferred embodiment of the invention the liquid monopropellant is made from di-isopropyl amine nitrate and anhydrous nitric acid wherein the salt constitutes 33% by weight of the monopropellant and the acid, 67%. When the nitric acid containing monopropellant impinges upon the dough, the heat of reaction raises the monoproellant to the ignition point. When the temperature of the chamber is sufiicient to support spontaneous combustion of the monopropellant, the igniter is decomposed. Thus, the invention provides a relatively simple method for starting combustion in a rocket motor.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An igniter for the decomposition of di-isopropyl amine nitrate dissolved in anhydrous nitric acid, which consists essentially of a paste of by weight lithium hydride and 15% by weight of rubber cement.

2. The method of igniting the monopropellant di-isopropyl amine nitrate dissolved in anhydrous nitric acid in a rocket motor having a reaction chamber, which comprises spraying the di-isopropyl amine nitrate against a paste of 85% by weight of powdered lithium hydride and 15% by weight of rubber cement located within the chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,573,471 Malina et al. Oct. 30, 1951 2,636,342 Cade Apr. 28, 1953 2,645,079 Doumani et a1 July 14, 1953 2,648,190 Maisner Aug. 11, 1953 2,739,981 Szabo et al Mar. 27, 1956 FOREIGN PATENTS 655,585 Great Britain July 25, 1951 742,283 Great Britain Dec. 21, 1955 

2. THE METHOD OF IGNITING THE MONOPROPELLANT DI-ISOPROPYL AMINE NITRATE DISSOLVED INANHYDROUS NITRIC ACID IN A ROCKET MOTOR HAVING A REACTION CHAMBER, WHICH COMPRISES SPRAYING THE DI-ISOPROPYL AMINE NITRATE AGAINST A PASTE OF 85% BY WEIGHT OF POWDERED LITHIUM HYDRIDE AND 15% BY WEIGHT OF RUBBER CEMENT LOCATED WITHIN THE CHAMBER. 